1. Field of the Invention
The present invention relates to the field of hardware tool bits, and more particularly, the present invention relates to a device for removing damaged fasteners still embedded or otherwise engaged with a workpiece.
2. Description of the Prior Art
The use of fasteners, such as screws, bolts, and other threaded joining devices continues to increase. However, the more a fastener is used, the more likely that its head becomes rounded off, or the fastener is broken, or otherwise rendered useless. At that point, the fasteners must be removed, and/or the workpiece replaced or abandoned.
A myriad of screw removing bits exist. Generally, the bits are typical in that each utilizes a rotating tool shaft, such as the shaft of a screw driver, either manually or power-driven. The second end of the bit is configured to impart rotational torque to the fastener while the latter is still held fast by the workpiece.
The second end of the bit mimics the end of a standard drill bit. Several broken bolt extractors feature a left-handed cutting edge. For example, U.S. Pat. No. 4,777,850 discloses two such edges. However, such devices still require considerable power to impart the rotational torque necessary to “bite” into the fastener to begin left-handed extraction.
U.S. Pat. No. 6,595,730 B2 awarded to Bergamo on Jul. 22, 2003 discloses a bit for removing damaged screws. This device is designed to engage the exterior surface of the fasteners and not interior surfaces of the fastener. As such, “purchase” of the fastener by the device is relegated to that exterior surface.
Another example of a prior art extraction device is the tool disclosed in German patent DE 19526631 A1. The tool depicts two cutting edges that drill a hole in a “frozen” screw/bolt or rivet when rotated in a first direction. The two cutting edges also are suitable for loosening the same fastener after drilling the hole in the fastener thereby providing a single tool that performs two functions to reduce the extraction time to remove a fastener from a workpiece. The problem with this tool is that a recess must be present in the fastener to better facilitate removal from the workpiece. The German tool cannot be used to remove a fastener having a slotted surface configuration unless the fastener includes a recess with a depth sufficient to allow the two cutting edges to insert therein. Otherwise, the slotted head fastener would be damaged during removal.
A need exists in the art for a broken bolt or broken screw extraction device to facilitate easier removal of fasteners held tight by a workpiece. The device should be able to be utilized with hand-actuated handles or with electrically activated (including battery operated) tools. The device should engage as much of the interior surface of a wayward fastener so as to decrease the likelihood of a spin off of the device from the fastener while concomitantly increasing the likelihood of extraction of the fastener with minimal force required.